Vehicle speed limiter

ABSTRACT

A vehicle has a straddle seat, a handlebar, an engine, an electronic control unit (ECU), a throttle valve, a throttle valve actuator, and a throttle operator. A throttle operator position sensor senses a throttle operator position. A vehicle speed sensor senses a vehicle speed. The ECU sends a control signal to the throttle valve actuator based on the throttle operator position and the vehicle speed. The throttle valve actuator adjusts the opening of the throttle valve in response to the control signal. If the vehicle speed is lower than a predetermined maximum vehicle speed, the throttle valve actuator adjusts the opening of the throttle valve based on the throttle operator position signal. If the vehicle speed is higher than the predetermined maximum vehicle speed, the throttle valve actuator reduces the degree of opening of the throttle valve. A method of controlling an engine is also disclosed.

CROSS-REFERENCE

The present application claims priority to U.S. Provisional PatentApplication No. 60/871,684, filed Dec. 22, 2006, entitled“Throttle-By-Wire System”, the entirety of which is enclosed herewith.

FIELD OF THE INVENTION

The present invention relates to an engine control method and a vehiclehaving an engine controlled by the method.

BACKGROUND OF THE INVENTION

Most recreational vehicles, such as all-terrain vehicles (ATVs),snowmobiles, and personal watercraft, are powered by an internalcombustion engine. The operation of the engine generally is controlledby adjusting the quantity of air and fuel the combustion chambers of theengine receive, and by controlling the timing of the ignition of theair/fuel mixture in the combustion chamber. In the case of fuel injectedengines, the timing of the injection of the fuel can also be controlled.

Recreational vehicles typically have one or more throttle valves in theengine's air intake system which are mechanically connected to a driveroperated throttle operator, generally by a control cable. The throttleoperator, generally in the form of a lever or a twist grip on ahandlebar of the vehicle, is used by the driver to open and close thethrottle valves to adjust the quantity of air going to the combustionchambers of the engine. An electronic control unit (ECU) located in thevehicle then controls the engine's ignition system, and in the case offuel injected engine, the engine's fuel injection system, accordingly.In order to have the engine generate more power, the driver would usethe throttle operator to cause the throttle valve to open further.Similarly, in order to have the engine generate less power, the driverwould use the throttle operator to cause the throttle valve to close.For example, in the case of an ATV moving on a level surface, openingthe throttle valve results in the ATV accelerating and closing thethrottle valve results in the ATV decelerating.

In some instances, it is desirable to limit the power generated by theengine, to limit the maximum speed of the engine or to have a cruisecontrol function on the vehicle for example. Since in theabove-described vehicles the degree of opening of the throttle valve iscontrolled by the driver of the vehicle, this leaves the ECU to controlthe ignition and, where available the injection, in order to limit thepower of the engine. For example, when the engine reaches apredetermined maximum speed, the ECU will control the engine such thatsome of the spark plugs are not fired and/or that fuel is not injectedin every combustion chamber. This control strategy results however in arough engine operation which is undesirable.

Recent developments in the field of automotive electronics now allowthese vehicles to be equipped with what is known as a throttle-by-wiresystem. In such vehicles, a throttle operator position sensor senses theposition of the throttle operator, transmits this position to the ECU,and the ECU sends a signal to a throttle valve actuator, an electricactuator for example, to adjust the degree of opening of the throttlevalve based on the position of the throttle operator. This way, thedegree of opening of the throttle valve is also a variable, in additionto the ignition and fuel injection, that can be adjusted by the ECU.Vehicles using such systems can therefore use the degree of opening ofthe throttle valve to limit the speed of the engine. When apredetermined maximum engine speed is reached or exceeded, the ECU willnot cause the throttle valve to be opened further or will cause thedegree of opening of the throttle valve to be reduced notwithstandingthe fact that the signal from the operator position sensor communicatedto the ECU indicates a desire by the driver to increase the speed of theengine.

This greatly improves the control of the engine, however controlling theengine based on the engine speed may not be ideal in some instances. Forexample, regulations prevent personal watercraft manufacturers frommaking personal watercraft that can exceed 105 km/h (65 MPH). For thesame engine speed, the personal watercraft will go at a different speeddepending on the load on the vehicle (i.e. weight of the driver,passengers, and items carried on board). Therefore, the predeterminedmaximum engine speed must be selected such that the personal watercraftwill not exceed 100 km/h no matter how light the load on it is. Thiscauses a reduced performance of the personal watercraft when the load isincreased (driver with passengers for example) since it will have alower maximum speed than when a lighter load is present (only the driverfor example). Similar instances also exist for land vehicles.

Therefore, there is a need for a method which ameliorates the control ofthe engine of the vehicle to control the performance of a vehicle.

Throttle-by-wire systems also simplify the implementation of cruisecontrol systems on vehicles. In automotive applications the cruisecontrol is typically engaged by pressing a button on the steering wheelof the vehicle and can be disengaged by pressing the button again or bypressing the brake. However, this method may not be applicable to everytype of vehicle, such as personal watercraft given their lack of brakes.

Therefore there is a need for a novel cruise control engine operationmode.

It is generally preferred that the performance of a vehicle be morerestricted when it is operated in the reverse direction than when it isgoing forward. This can be achieved by using a mechanical transmissionthat reduces the speed of rotation from the engine to the wheels of thevehicle, for example, along with the direction of rotation when thereverse position of the transmission is selected. However, suchtransmissions can be complex and add substantial weight to the vehicle,especially for vehicles using a continuously variable transmission(CVT).

Therefore there is a need for a method to ameliorate the control of theperformance of a vehicle operated in a reverse direction.

SUMMARY OF THE INVENTION

It is an object of the present invention to ameliorate at least some ofthe inconveniences present in the prior art.

It is an object of the present invention to provide a vehicle that hasan ECU that controls an engine of the vehicle by sending a controlsignal to a throttle valve actuator such that the vehicle does notexceed a predetermined maximum vehicle speed.

It is a further object of the present invention to provide a method ofcontrolling an engine of a vehicle by adjusting a degree of opening of athrottle valve such that the vehicle does not exceed a predeterminedmaximum vehicle speed.

In one aspect, the invention provides a vehicle having a vehicle bodyand a straddle seat for a driver. The seat is associated with thevehicle body. A handlebar for steering the vehicle is disposed forwardlyof the straddle seat. An engine is associated with the vehicle body forpowering the vehicle. The engine has at least one combustion chamber. Anelectronic control unit (ECU) on the vehicle controls an operation ofthe engine. A throttle body is in fluid communication with the at leastone combustion chamber. A throttle valve is disposed in the throttlebody for controlling an amount of air supplied to the at least onecombustion chamber. A throttle valve actuator is operatively connectedto the throttle valve and is in electronic communication with the ECU. Athrottle operator is mounted on the handlebar. A throttle operatorposition sensor senses a throttle operator position and is in electroniccommunication with the ECU for sending a signal representative of athrottle operator position to the ECU. A vehicle speed sensor senses avehicle speed and is in electronic communication with the ECU forsending a signal representative of a vehicle speed to the ECU. The ECUsends a control signal to the throttle valve actuator based on thethrottle operator position signal and the vehicle speed signal. Thethrottle valve actuator adjusts a degree of opening of the throttlevalve in response to the control signal. If the vehicle speed is lowerthan a predetermined maximum vehicle speed, the control signal causesthe throttle valve actuator to adjust the degree of opening of thethrottle valve based on the throttle operator position signal. If thevehicle speed is higher than the predetermined maximum vehicle speed,the control signal causes the throttle valve actuator to reduce thedegree of opening of the throttle valve.

In an additional aspect, if the vehicle speed is higher than thepredetermined maximum vehicle speed, the control signal causes thethrottle valve actuator to reduce the degree of opening of the throttlevalve notwithstanding a fact that the signal representative of thethrottle operator position communicated to the ECU indicates a desire bythe driver to increase the speed of the vehicle.

In a further aspect, if the vehicle speed is equal to the predeterminedmaximum vehicle speed, the degree of opening of the throttle valve isnot increased notwithstanding a fact that the signal representative ofthe throttle operator position communicated to the ECU indicates adesire by the driver to increase the speed of the vehicle.

In an additional aspect, the throttle operator is selected from a groupconsisting of a thumb-actuated throttle lever, a finger-actuatedthrottle lever, and a twist grip.

In a further aspect, the vehicle also has a jet propulsion unitoperatively connected to the engine. The vehicle body has a hull and adeck disposed on the hull. The engine is disposed between the hull andthe deck.

In an additional aspect, the vehicle speed sensor is selected from agroup consisting of a paddle wheel, a GPS unit, and a pitot tube.

In a further aspect, the vehicle also has only three wheels associatedwith the vehicle body.

In an additional aspect, the vehicle also has at least one of at leastfour wheels associated with the vehicle body and an endless trackassociated with the vehicle body.

In a further aspect, the vehicle speed sensor includes a GPS unit.

In an additional aspect, the vehicle speed sensor senses a rotationalspeed of a shaft of the vehicle.

In a further aspect, the vehicle also has a fuel injection system forinjecting fluid in the at least one combustion chamber, an ignitionsystem for igniting a mixture of fuel and air in the at least onecombustion chamber, and a throttle valve position sensor for sensing thedegree of opening of the throttle valve and in electronic communicationwith the ECU for sending a signal representative of a throttle valveposition to the ECU. The ECU controls at least one of the fuel injectionsystem and the ignition system based on the throttle valve positionsignal.

In an additional aspect, the vehicle also has a throttle valve positionsensor for sensing the degree of opening of the throttle valve and inelectronic communication with the ECU for sending a signalrepresentative of a throttle valve position to the ECU. The ECUestablishes a desired degree of opening of the throttle valve based onthe throttle operator position signal. The ECU generates the controlsignal both by: (a) comparing the desired degree of opening of thethrottle valve to the degree of opening of the throttle valve, and (b)comparing the vehicle speed to the predetermined maximum vehicle speed.

In a further aspect, when a variation in the vehicle speed signal occurswhich is greater than a predetermined acceptable variation, the ECUignores the variation in the vehicle speed signal for a predeterminedtime delay.

In an additional aspect, when a failure of the vehicle speed sensor isdetected, the ECU limits the operation of the engine to one of a defaultmaximum engine speed and a default maximum engine torque. The one of thedefault maximum engine speed and the default maximum engine torque isselected such that when the engine operates at the one of the defaultmaximum engine speed and the default maximum engine torque, the vehiclespeed is less than the predetermined maximum vehicle speed.

In a further aspect, the vehicle also has a key receiver disposed on thevehicle body for receiving one of at least two keys that can be used topermit operation of the vehicle. The key receiver is in electroniccommunication with the ECU. The predetermined maximum vehicle speed isdetermined from information contained on the one of the at least twokeys which is received in the key receiver. The predetermined maximumvehicle speed is different for each of the at least two keys.

In an additional aspect, the predetermined maximum vehicle speed ispermanently stored in the ECU.

In a further aspect, when a variation in the vehicle speed signal occurswhich is greater than a predetermined maximum acceptable variation, theECU controls the engine such that a speed of rotation of the engine isreduced.

In another aspect, the invention provides a method of controlling anengine of a vehicle. The engine has at least one combustion chamber. Thevehicle has a throttle operator, a throttle body in fluid communicationwith the at least one combustion chamber, a throttle valve disposed inthe throttle body for controlling an amount of air supplied to the atleast one combustion chamber, and a throttle valve actuator operativelyconnected to the throttle valve for adjusting a degree of opening of thethrottle valve. The method comprises sensing a throttle operatorposition, sensing a vehicle speed, and comparing the vehicle speed to apredetermined maximum vehicle speed. If the vehicle speed is lower thanthe predetermined maximum vehicle speed, the degree of opening of thethrottle valve is adjusted based on the throttle operator position. Ifthe vehicle speed is higher than the predetermined maximum vehiclespeed, the degree of opening of the throttle valve is reduced until thevehicle speed is at the predetermined maximum speed.

In a further aspect, if vehicle speed is greater than the predeterminedmaximum vehicle speed, a driver instruction to increase the degree ofopening of the throttle valve is not implemented.

In an additional aspect, if vehicle speed is equal to the predeterminedmaximum vehicle speed, a driver instruction to increase the degree ofopening of the throttle valve is not implemented.

In a further aspect, the step of sensing the vehicle speed includessensing one of a rotational speed of a paddle wheel mounted to thevehicle, a rotational speed of a shaft of the vehicle, and a pressure ofa fluid in which the vehicle is used.

In an additional aspect, the step of sensing the vehicle speed includesdetermining a change in position of the vehicle over a period of timebased on information obtained from a GPS unit.

In a further aspect, the method also comprises sensing the degree ofopening of the throttle valve, and controlling at least one of a fuelinjection system and an ignition system based on the degree of openingof the throttle valve.

In an additional aspect, the method also comprises sensing the degree ofopening of the throttle valve. The step of adjusting the degree ofopening of the throttle valve includes establishing a desired degree ofopening of the throttle valve based on the throttle operator position.If the desired degree of opening of the throttle valve is less than thedegree of opening of the throttle valve, the degree of opening of thethrottle valve is decreased until the degree of opening of the throttlevalve is equal to the desired degree of opening of the throttle valve.If the desired degree of opening of the throttle valve is greater thanthe degree of opening of the throttle valve, the degree opening of thethrottle valve is increased until one of a first condition and a secondcondition is met. The first condition is that the degree of opening ofthe throttle valve is equal to the desired degree of opening of thethrottle valve. The second condition is that the vehicle speed is equalto the predetermined maximum vehicle speed.

In a further aspect, the method also comprises ignoring a variation inthe vehicle speed which is greater than a predetermined maximumacceptable variation for a predetermined time delay when sensing thevehicle speed, and using the vehicle speed prior to the variation in thevehicle speed when comparing the vehicle speed to the predeterminedmaximum vehicle speed during the predetermined time delay.

In an additional aspect, the method also comprises sensing for failureof a vehicle speed sensor, and limiting the engine to one of a defaultmaximum engine speed and a default maximum engine torque when failure ofthe vehicle speed sensor is sensed. The one of the default maximumengine speed and the default maximum engine torque is selected such thatwhen the engine is at the one of the default maximum engine speed andthe default maximum engine torque, the vehicle speed is lower than thepredetermined maximum vehicle speed.

In a further aspect, the method also comprises obtaining informationcontained on a key inserted in a key receiver of the vehicle, and usingthe information contained on the key to determine the predeterminedmaximum vehicle speed.

In an additional aspect, the method also comprises reducing a speed ofrotation of the engine when a variation in the vehicle speed is greaterthan a predetermined maximum acceptable variation.

Embodiments of the present invention each have at least one of theabove-mentioned objects and/or aspects, but do not necessarily have allof them.

Additional and/or alternative features, aspects, and advantages of theembodiments of the present invention will become apparent from thefollowing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a right side elevation view of a snowmobile;

FIG. 2 is a right side elevation view of a personal watercraft;

FIG. 3 is a right side elevation view of an ATV;

FIG. 4 is a schematic representation of the various sensors and vehiclecomponents present in a vehicle in accordance with the presentinvention;

FIG. 5 is a logic diagram illustrating a basic control of the engine'signition and fuel injection systems;

FIG. 6 is a logic diagram illustrating a control scheme adopted by theECU when a sudden variation in vehicle speed occurs;

FIG. 7 is a logic diagram illustrating a method for controlling themaximum vehicle speed of a vehicle;

FIG. 8 is a logic diagram illustrating a method for controlling theengine when a failure of the vehicle speed sensor occurs;

FIG. 9A is a logic diagram illustrating a method for controlling theengine in a cruise control mode;

FIG. 9B is a logic diagram illustrating an alternative method forcontrolling the engine in a cruise control mode;

FIG. 10 is a logic diagram illustrating a method for controlling theengine in an off-throttle steering mode;

FIG. 11 is a logic diagram illustrating a method for controlling amaximum degree of opening of the throttle valve when a vehicle operatesin a reverse direction;

FIG. 12 is a logic diagram illustrating a method for controlling amaximum vehicle speed when a vehicle operates in a reverse direction;

FIG. 13 is a logic diagram illustrating a method of controlling amaximum vehicle performance based on the vehicle operation direction;and

FIG. 14 is a logic diagram illustrating a control scheme adopted by theECU when a sudden increase in vehicle speed occurs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described with respect to vehicles havinga single throttle body, a single throttle valve, and a single throttlevalve actuator, but it should be understood that vehicles havingmultiple throttle bodies and throttle valves with one or more throttlevalve actuators are also contemplated.

The present invention will also be described with respect to asnowmobile 10, a personal watercraft 70, and an ATV 150, but it shouldbe understood that aspects of the invention could also be used on othertypes of vehicles such as boats, motorcycles, or engine-poweredtricycles. Each of those vehicles will now be described.

Referring to FIG. 1, a snowmobile 10 includes a forward end 12 and arearward end 14 which are defined consistently with a travel directionof the vehicle. The snowmobile 10 includes a vehicle body in the form ofa frame or chassis 16 which normally includes a rear tunnel 18, anengine cradle portion 20 and a front suspension assembly portion 22. Anengine 24, which is schematically illustrated in FIG. 1, is carried bythe engine cradle portion 20 of the frame 16. A ski and steeringassembly (not indicated) is provided, in which two skis 26 arepositioned at the forward end 12 of the snowmobile 10 and are attachedto the front suspension assembly portion 22 of the frame 16 through afront suspension assembly 28. The front suspension assembly 28 includesski legs 30, supporting arms 32 and ball joints (not shown) foroperatively joining the respective ski legs 30, supporting arms 32 and asteering column 34. The steering column 34 at its upper end is attachedto a steering device such as a handlebar 36 which is positioned forwardof a rider and behind the engine 24 to rotate the ski legs 30 and thusthe skis 26, in order to steer the vehicle. A throttle operator in theform of a finger-actuated throttle lever 37 is mounted to the handlebar36. Other types of throttle operators, such as a thumb-actuated throttlelever and a twist grip, are also contemplated. The function of thefinger-actuated throttle lever 37 will be discussed in greater detailbelow.

An endless drive track 38 is positioned at the rear end 14 of thesnowmobile 10. The drive track 38 is disposed generally under the tunnel18, being connected operatively to the engine 24 through a belttransmission system 40 which is schematically illustrated by brokenlines in FIG. 1. Thus, the endless drive track 38 is driven to run abouta rear suspension assembly 42 for propulsion of the snowmobile 10. Aspeed sensor (not shown) senses the speed of rotation of a shaft (notshown) transmitting power from the transmission system 40 to the endlessdrive track 38. An ECU (not shown in FIG. 1) connected to the speedsensor converts the rotational speed of the shaft to the speed of thesnowmobile 10 in kilometers or miles per hour, depending on the rider'spreference. The speed sensor could also be used to sense the rotationalspeed of one of the endless track 38. The speed sensor could alsoinclude a GPS unit, in which case the speed of the snowmobile 10 wouldbe determined by calculating the change in position of the snowmobile 10over a period of time based on information obtained from the GPS unit.

The rear suspension assembly 42 includes a pair of slide rails 44 insliding contact with the endless drive track 38. The rear suspensionassembly 42 also includes one or more shock absorbers 46 which mayfurther include a coil spring (not shown) surrounding the individualshock absorbers 46. Front and rear suspension arms 48 and 50 areprovided to attach the slide rails 44 to the frame (chassis) 16. One ormore idler wheels 52 are also provided in the rear suspension assembly42.

At the front end 12 of the snowmobile 10, fairings 54 enclose the engine24 and the belt transmission system 40, thereby providing an externalshell that not only protects the engine 24 and the belt transmissionsystem 40, but can also be decorated to make the snowmobile 10 moreaesthetically pleasing. Typically, the fairings 54 include a hood (notindicated) and one or more side panels which can be opened to allowaccess to the engine 24 and the belt transmission system 40 when this isrequired, for example, for inspection or maintenance of the engine 24and/or the belt transmission system 40. In the particular snowmobile 10shown in FIG. 1, the side panels can be opened along a vertical axis toswing away from the snowmobile 10. A windshield 56 may be connected tothe fairings 54 near the front end 12 of the snowmobile 10 or directlyto the handlebar 36. The windshield 56 acts as a wind screen to lessenthe force of the air on the rider while the snowmobile 10 is moving.

The engine 24 is a type of internal combustion engine that is supportedon the frame 16 and is located at the engine cradle portion 20. Theinternal construction of the engine 24 may be of any known type, howeverthe engine 24 drives an engine output shaft (not shown) that rotatesabout a horizontally disposed axis that extends generally transverselyto a longitudinal centerline 61 of the snowmobile 10. The engine outputshaft drives the belt transmission system 40 for transmitting torque tothe endless drive track 38 for propulsion of the snowmobile 10.

A straddle-type seat 58 is positioned atop the frame 16 and extends fromthe rear end 14 of the snowmobile 10 to the fairings 54. A rear portionof the seat 58 may include a storage compartment or can be used toaccommodate a passenger seat (not indicated). Two footrests 60 arepositioned on opposite sides of the snowmobile 10 below the seat 58 toaccommodate the driver's feet.

Turning now to FIG. 2, a personal watercraft 70 has a vehicle body madeof two main parts. These parts of the watercraft 70 are the hull 72 andthe deck 74. The hull 72 buoyantly supports the watercraft 70 in thewater. The deck 74 is designed to accommodate a rider and, in somewatercraft, one or more passengers. The hull 72 and deck 74 are joinedtogether at the bond line 76 by an adhesive. Rivets or other fastenersmay also join the hull 72 and deck 74. A bumper 78 generally covers thebond line 76 helping to prevent damage to the outer surface of thewatercraft 70 when the watercraft 70 is docked. The volume createdbetween the hull 72 and the deck 74 is known as the engine compartment(not shown). The engine compartment accommodates the engine 80(schematically illustrated in FIG. 2) as well as the exhaust system, gastank, electrical system (battery, electronic control unit . . . ), airbox, storage bins (not shown) and other elements required or desired forthe watercraft 70. One of the challenges when designing a watercraft 70is to fit all of these elements into this relatively small volume.

As seen in FIG. 2, the deck 74 has a centrally positioned straddle-typeseat 82 placed on top of a pedestal 84 to accommodate a rider in astraddling position. A grab handle 86 is provided between the pedestal84 and the straddle-type seat 82 at the rear of the straddle-type seat82 to provide a handle onto which a passenger may hold on. Thestraddle-type seat 82 may comprise a first and second seats 88 and 90respectively. First and second seats 88, 90 are preferably removablyattached to the pedestal 84 by a hook and tongue assembly (not shown) atthe front of each seat 88, 90 and by a latch assembly (not shown) at therear of each seat 88, 90, or by any other known attachment mechanism.One of the seats 88, 90 covers an engine access opening (not shown),defined by a top portion of the pedestal 84, which provides access tothe engine 80, and the other of the seats 88, 90 will generally cover aremovable storage box (not shown). A glove box may also be provided infront of the straddle type seat 82. A tow hook 92 is also placed on arear portion of the pedestal 84 to allow watercraft 70 to tow, forexample, a water-skier or an inflatable water toy.

The watercraft 70 has a pair of generally upwardly extending wallslocated on either side of the watercraft 70 known as gunwales or gunnels94. The gunnels 94 help to prevent the entry of water in the watercraft70, provide lateral support for the rider's feet, and also providebuoyancy when turning the watercraft 70, since personal watercraft rollslightly when turning. Towards the rear of the watercraft 70 the gunnels94 extend inwardly to act as heel rests 96. Heel rests 96 allow apassenger riding the watercraft 70 facing the towards the rear, to spota water-skier for example, to place his heels on the heel rests 96,thereby providing him with a more stable riding position. It should benoted that heel rests 96 could also be separate from the gunnels 94.

Located on either side of the pedestal 84, between the pedestal 84 andthe gunnels 94 are a pair of footrests (not shown). The footrests aredesigned to accommodate a rider's feet in various riding positions. Tothis effect the forward portions of the footrests are angled upwardly.The remaining portions of the footrests are generally horizontal. Thefootrests may be covered by carpeting made of a rubber-type material toprovide additional comfort and feet traction for the rider. A reboardingplatform 98 is provided at the rear of the watercraft 70 to allow therider or a passenger to easily reboard the watercraft 98 from the water.Carpeting may also cover the reboarding platform 98. A retractableladder (not shown) may be affixed to the transom 100 to facilitateboarding the watercraft 70 from the water onto the reboarding platform98.

A handlebar or helm assembly 102 is positioned forwardly of thestraddle-type seat 82. The helm assembly 102 has a central helm portion104, that may be padded, and a pair of steering handles 106. One of thesteering handles 106 is provided with a throttle operator in the form ofa thumb-actuated throttle lever 108. Other types of throttle operators,such as a finger-actuated throttle lever and a twist grip, are alsocontemplated. The function of the thumb-actuated throttle lever 108 willbe discussed in greater detail below. The central helm portion 104 mayalso have buttons (not shown) that allow the rider to modify what isdisplayed (speed, engine rpm, time . . . ) on the display cluster 110located forwardly of the helm assembly 102, to change a condition of thewatercraft 70 such as trim (the pitch of the watercraft 70), or toengage a watercraft operation mode such as a cruise control mode. Thehelm assembly 102 may also be provided with a key receiving post (notshown), preferably located near a center of the central helm portion104. The key receiving post is adapted to receive a key attached to alanyard so as to allow starting of the watercraft 70. It should be notedthat the key receiving post may be placed in any suitable location onthe watercraft 2.

The watercraft 70 is provided with a hood 112 located forwardly of thehelm assembly 102. A hinge (not shown) is attached between a forwardportion of the hood 112 and the deck 74 to allow the hood 112 to move toan opened position to provide access to a front storage bin (not shown).A latch (not shown) located at a rearward portion of hood 112 locks thehood 112 into a closed position. When in the closed position, the hood112 prevents water from entering front storage bin. Rearview mirrors 114are positioned on either side of the hood 112 to allow the rider to seebehind him.

The hull 72 is provided with a combination of strakes 116 and chines118. A strake 116 is a protruding portion of the hull 72. A chine 118 isthe vertex formed where two surfaces of the hull 72 meet. It is thiscombination of strakes 116 and chines 118 that will give the watercraft70 its riding and handling characteristics.

Sponsons 120 are located on either of the hull 72 near the transom 100.The sponsons 120 have an arcuate undersurface, which give the watercraft70 both lift while in motion and improved turning characteristics.

A hook 122 is located at the bow 124 of the watercraft 70. The hook 122is used to attach the watercraft 70 to a dock when it is not in use.

The watercraft 70 is propelled by a jet pump 126. It is contemplatedthat other types of propulsion system, such as propellers, could beused. The jet pump 126 pressurizes water and accelerates it to createthrust. The water is first scooped from under the hull 72 through aninlet grate 128. The inlet grate 128 prevents large rocks, weeds, andother debris from entering the jet propulsion system 126 since they maydamage it or negatively affect its performance. Water then flows throughthe water intake ramp (not shown). From the intake ramp, water thenenters the jet pump 126. The jet pump 126 is located in what is known asthe tunnel (not shown). The tunnel is opened towards the rear, isdefined at the front, sides, and top by the hull, and at the bottom bythe ride plate 130. The ride plate 130 is the surface on which thewatercraft 70 rides or planes. The jet pump 126 is made of two mainparts: the impeller (not shown) and the stator (not shown). The impelleris coupled to the engine 80 by one or more shafts 132, such as adriveshaft and an impeller shaft. The rotation of the impellerpressurizes the water, which then moves over the stator that is made ofa plurality of fixed stator blades (not shown). The role of the statorblades is to decrease the rotational motion of the water so that almostall the energy given to the water is used for thrust, as opposed toswirling the water. Once the water leaves the jet pump 126, it goesthrough the venturi (not shown). Since the venturi's exit diameter issmaller than its entrance diameter, the water is accelerated further,thereby providing more thrust. A steering nozzle 134 is pivotallyattached to the venturi through a vertical pivot point. The steeringnozzle 134 is operatively connected to the helm assembly 102 via apush-pull cable (not shown) such that when the helm assembly 102 isturned, the steering nozzle 134 pivots, redirects the water coming fromthe venturi, so as to steer the watercraft 70 in the desired direction.In some watercraft, the steering nozzle 134 may be gimballed to allow itto move around a second horizontal pivot axis. The up and down movementof the steering nozzle 134 provided by this additional pivot axis isknown as trim, and controls the pitch of the watercraft 70.

When the watercraft 70 is in movement, its speed is measured by a speedsensor 136 attached to the transom 100 of the watercraft 70. The speedsensor 136 has a paddle wheel which is turned by the flow of water,therefore the faster the watercraft 70 goes, the faster the paddle wheelturns. An ECU (not shown in FIG. 2) connected to the speed sensor 136converts the pulse of the rotational speed of the rotational speed ofthe paddle wheel to the speed of the watercraft 70 in kilometers ormiles per hour, depending on the rider's preference. The speed sensor136 may also be placed in the ride plate 130 or any other suitableposition. Other types of speed sensors, such as pitot tube, could alsobe used. The speed sensor 136 could also include a GPS unit, in whichcase the speed of the watercraft 70 would be determined by calculatingthe change in position of the watercraft 70 over a period of time basedon information obtained from the GPS unit.

Some watercraft 70 have the ability to move in a reverse direction. Todo this a reverse gate 138 is used. The reverse gate 138 is pivotallyattached to the sidewalls of the tunnel or directly on the venturi orthe steering nozzle 134. To make the watercraft 70 move in a reversedirection, the rider pulls on a reverse handle 140 operatively connectedto the reverse gate 138. The reverse gate 138 then pivots in behind thesteering nozzle 134 and redirects the water leaving the jet pump 126towards the front of the watercraft 70, thereby thrusting the watercraft70 rearwardly.

Turning now to FIG. 3, an ATV 150 includes a frame 152 (portions ofwhich are shown in FIG. 3) to which is mounted a body 154 and aninternal combustion engine 156 for powering the vehicle. Also connectedto the frame 152 are at least three but preferably four wheels 158 withlow-pressure balloon tires 160 mounted rims 161 having a diameter from25 to 36 cm. It is contemplated that the ATV 150 could have only threewheels 158. The low-pressure balloon tires 160 are inflated to apressure of no more than 2 kg/cm² (i.e., no more than 196 kPa or 28 psi)and are adapted for off-road conditions and traversing rugged terrain.The ATV 150 further includes a straddle seat 162 mounted to the frame152 for supporting a driver and optionally one or more passengers.

The two front wheels 158 are suspended from the frame 152 by respectivefront suspension assemblies 164 while the two rear wheels 158 aresuspended from the frame 152 by respective rear suspension assemblies166.

Still referring to FIG. 3, the ATV 150 further includes a steeringassembly 168 which is rotationally supported by the frame 152 to enablea driver to steer the vehicle. The steering assembly 168 includes ahandlebar 170 connected to a steering column (not shown) for actuatingsteering linkages connected to left and right front wheels 158. Athrottle operator in the form of a thumb-actuated throttle lever 172 ismounted to the handlebar 170. Other types of throttle operators, such asa finger-actuated throttle lever and a twist grip, are alsocontemplated. The function of the thumb-actuated throttle lever 172 willbe discussed in greater detail below. A display cluster 174 is disposedforwardly of the steering assembly 168 to display information such asthe speed of the ATV 150 and the speed of rotation of the engine 156.

A transmission (not shown) is operatively connected between the engine156 and the wheels 158 as is known in the art. A shifter located nearthe steering assembly 168 enables a driver to select one of a pluralityof drive modes for the vehicle. The drive modes include park, neutral,reverse, low, and drive. A speed sensor (not shown) senses the speed ofrotation of one of the shafts (not shown) transmitting power from thetransmission to the wheels 158. An ECU (not shown in FIG. 2) connectedto the speed sensor converts the rotational speed of the shaft to thespeed of the ATV 150 in kilometers or miles per hour, depending on therider's preference. The speed sensor could also be used to sense therotational speed of one of the wheels 158. The speed sensor could alsoinclude a GPS unit, in which case the speed of the ATV 150 would bedetermined by calculating the change in position of the ATV 150 over aperiod of time based on information obtained from the GPS unit.

Turning now to FIG. 4, the various sensors and vehicle componentspresent in a vehicle in accordance with the present invention, such asthose described above, will now be described. As it would be understoodby those skilled in the art, not every sensor or component illustratedin FIG. 4 is required to achieve aspects of the present invention. Aswould also be understood by those skilled in the art, depending on theparticular aspect of the invention, some of the sensors and componentscould be omitted, some of the sensors and components could besubstituted by other types of sensor and components, and two or moresensors could be combined in a single sensor that can be used to performmultiple functions without departing from the scope of the presentinvention. For simplicity, and since like elements were given differentreference numerals in the above description of the various vehicles,these elements (such as the engine, ECU, and transmission) will be givena new reference numeral which will be used for the remainder of thedescription, unless specific reference is being made to one of theabove-described vehicles.

As can be seen in FIG. 4, the ECU 200 is in electronic communicationwith various sensors from which it receives signals and uses thesesignals to control the operation of the ignition system 216, the fuelinjection system 218 in the case of a fuel injected engine, and thethrottle valve actuator 214 in order to control the engine 202. Thespecific methods by which the ECU 200 controls the engine 202 will bedescribed in more detail below.

A throttle operator position sensor 204 senses a position of thethrottle operator 206 and sends a signal representative of the throttleoperator position to the ECU 200. The throttle operator 206 can be ofany type, but is preferably selected from a group consisting of athumb-actuated throttle lever, a finger-actuated throttle lever, and atwist grip. The throttle operator 206 is normally biased, typically by aspring, towards a position that is indicative of a desire for an idleoperation of the engine 202. In the case of a thumb or finger-actuatedthrottle lever, this corresponds to the position where the lever isfurthest away from the handle to which it is mounted. Depending on thetype of throttle operator 206, the throttle operator position sensor 204is generally disposed in proximity to the throttle operator 206 andsenses the movement of the throttle operator 206 or the lineardisplacement of a cable connected to the throttle operator 206. Thethrottle operator position sensor 204 is preferably in the form of amagnetic position sensor. In this type of sensor, a magnet is mounted tothe throttle operator 206 and a sensor chip is fixedly mounted inproximity to the magnet. As the magnet moves, due to movement of thethrottle operator 206, the magnetic field sensed by the sensor chipvaries. The sensor chip transmits a voltage corresponding to the sensedmagnetic field, which corresponds to the position of the throttleoperator 206, to the ECU 200. It is contemplated that the sensor chipcould be the one mounted to the throttle operator 206 and that themagnet could be fixedly mounted in proximity to the sensor chip. Thethrottle operator position sensor 204 could also be in the form of arheostat. A rheostat is a resistor which regulates current by means ofvariable resistance. In the present case, the position of the throttleoperator 206 would determine the resistance in the rheostat which wouldresult in a specific current being transmitted to the ECU 200.Therefore, this current is representative of the position of thethrottle operator 206. It is contemplated that other types of sensorscould be used as the throttle operator position sensor 204, such as apotentiometer which regulates voltage instead of current.

A vehicle speed sensor 208 senses the speed of the vehicle and sends asignal representative of the speed of the vehicle to the ECU 200. Inaddition to using this signal to control the engine 202, as will bedescribed below, the ECU 200 sends a signal to a speed gauge located inthe display cluster (110 in FIG. 2, 174 in FIG. 3) of the vehicle suchthat the speed gauge displays the vehicle speed to the driver of thevehicle. The vehicle speed sensor 208 can be of any type. The vehiclespeed sensor 208 can, for example, sense the speed of rotation of awheel of the vehicle or of one of the shafts transmitting power to thewheel which is then converted to or associated with a vehicle speed bythe ECU 200 or by a separate circuit associated with the vehicle speedsensor 208. The vehicle speed sensor 208 could also be a pitot tubewhich is used to determine the speed of the vehicle by using the staticand dynamic fluid pressures (air or water pressure depending on thevehicle type). In a watercraft, the vehicle speed sensor 208 could alsouse a paddle wheel, the specifics of which were explained above withrespect to personal watercraft 70. Alternatively, the vehicle speedsensor 208 could include a global positioning system (GPS unit 209). Byusing information from the GPS unit 209, the speed of the vehicle can bedetermined by calculating a change in position of the vehicle over aperiod of time which is normally a function of the GPS unit.

A throttle valve position sensor 210 senses the position (i.e. thedegree of opening) of the throttle valve 212 and sends a signalrepresentative of the position of the throttle valve 212 to the ECU 200.The throttle valve position sensor 210 acts as a feedback to the ECU 200since the ECU 200 uses the signal received from the throttle valveposition sensor 210 to determine if the throttle valve actuator 214 hasmoved the throttle valve 212 to the desired position and can makeadjustments accordingly, as will be described in greater detail below.The ECU 200 can also use the signal from the throttle valve positionsensor 210 actively to control the ignition system 216 and the fuelinjection system 218 along with other signals depending on the specificcontrol scheme used by the ECU 200. The throttle valve position sensor210 can be any suitable type of sensor such as a rheostat and apotentiometer as described above with respect to the throttle operatorposition sensor 204. Depending on the type of throttle valve actuator214 being used, a separate throttle valve position sensor 210 may not benecessary. For example, a separate throttle operator position sensor 204would not be required if the throttle valve actuator 214 is a servomotor since servo motors integrate their own feedback circuit thatcorrects the position of the motor and thus have an integrated throttleposition sensor 204.

A key receiver 220 is disposed on the vehicle body and is in electroniccommunication with the ECU. The key receiver 220 is adapted to receive akey 222. In a first embodiment, the key 222 is in inserted in the keyreceiver 220 and if it is the correct key 222, the key 222 can be turnedin the key receiver 220 and a signal is sent to the ECU to start theengine 202. In a mechanical key receiver 220 and key 222 system, onlythe correct key 222 has the proper tooth pattern which will allow it tobe turned in the key receiver 220. In an electronic key receiver 220 andkey 222 system, an electronic chip in or on the key 222 contains a codeidentifying the key 222. When the key 222 is inserted in the keyreceiver 220, a signal representative of the code is sent to the ECU 200and the engine 202 will only start if the chip on the key 222 containsthe proper code. In a preferred embodiment, the key receiver 220 and key222 system is an electronic system as described above, but instead ofturning the key 222 in the key receiver 220 to start the engine 202,there is a separate “start/stop” button that needs to be pressed by thedriver of the vehicle to start the engine 202 once the key 222 isinserted in the key receiver 220. Once the engine 202 has been started,pressing the “start/stop” button or removing the key 222 from the keyreceiver 220 will send a signal to the ECU 200 to stop the engine 202.The key 222 is preferably attached to a lanyard that can be attached tothe driver of the vehicle, such that if the driver becomes separatedfrom the vehicle, the key 222 will be removed from the key receiver 220,causing the engine 202, and therefore the vehicle, to stop. In thepreferred embodiment, the vehicle has more than one key 222 that willpermit the engine 202 to be started. For each of these keys, keys 222and 224 for example, the electronic chip also contains informationregarding the performance limits of the vehicle or engine 202, such asmaximum vehicle speed, engine speed, or engine torque, as will bedescribed in further detail below. A signal representative of thisinformation is sent to the ECU 200 when the key 222 or 224 is insertedin the key receiver 220. For example key 222 may permit the vehicle tooperate up to a speed of 100 km/hour, while key 224 limits the maximumspeed to 30 km/hour. U.S. Pat. No. 6,772,061, entitled “System, Method,and Apparatus for Controlling Vehicle Performance”, issued on Aug. 3,2004, the entirety of which is incorporated herein by reference,describes a system where the vehicle performance is restricted based oninformation contained on a key.

A vehicle operation direction sensor senses the vehicle operationdirection and sends a signal representative of the vehicle operationdirection (i.e. the forward or reverse direction of travel) to the ECU200. The vehicle operation direction sensor can be in the form of ashifter sensor 226 for sensing the vehicle operation direction selectedby a shifter 228 of the vehicle and sending a signal representative ofthe direction to the ECU 200. Although contemplated, the shifter sensor226 does not need to sense every possible position of the shifter 228.Instead, the shifter sensor could be adapted to sense only if theshifter 228 is in a position indicative of a reverse vehicle operationdirection (e.g. that the reverse gear has been selected by the shifterfor a vehicle equipped with a transmission). Alternatively, for vehicleequipped with a transmission 230 having one or more forward gears and atleast one reverse gear and which is operatively connected between theengine 202 and the propulsion 232 (the wheels for example), the vehicleoperation direction sensor can be in the form of a transmission positionsensor 234 for sensing which of the gears has been selected by theshifter 228 to determine the vehicle operation direction. Alternatively,the vehicle operation direction sensor can be in the form of an enginerotation direction sensor 236. As described in U.S. Pat. No. 5,794,574,entitled “System for Reversing 2 Stroke Engine”, issued Aug. 18, 1998,the entirety of which is incorporated herein by reference, it ispossible to reverse the direction of rotation of the engine 202 andtherefore reverse the vehicle operation direction by doing so.Therefore, in vehicles using such an engine control strategy, it ispossible to determine the vehicle operation direction by using an enginerotation direction sensor 236 to sense the direction of rotation of theengine 202. It is contemplated that the engine speed sensor 238,described below, could be used to perform the function of the enginerotation direction sensor 236. It is also contemplated that the vehiclespeed sensor 208 (depending on its type) or the GPS unit 209 could beused as the vehicle operation direction sensor.

An engine speed sensor 238 senses a speed of rotation of the engine 202and sends a signal representative of the speed of rotation of the engine202 to the ECU 200. Typically, an engine, such as engine 202, has atoothed wheel disposed on and rotating with a shaft of the engine, suchas the crankshaft or output shaft. The engine speed sensor 238 islocated in proximity to the toothed wheel and sends a signal to the ECU200 each time a tooth passes in front it. The ECU 200 can then determinethe engine rotation speed by calculating the time elapsed between eachsignal. The speed of rotation of the engine can be used by the ECU 200to calculate the engine torque. Should the vehicle speed sensor 208fail, embodiments of the present invention will then move to an enginecontrol strategy which uses the signal from the engine speed sensor 238,as will be explained below.

A cruise control switch 240 in electronic communication with the ECU 200is used to engage and disengage a cruise control operation mode of theengine 202 where the vehicle will operate at a constant speed, as willbe described in greater detail below. The cruise control switch 240 canbe a dedicated switch or it could be combined with a switch alreadypresent on the vehicle. For example, most personal watercraft, such aspersonal watercraft 70, have a “set” and a “mode” button to controlfunctions on the display cluster, one of which could perform its normalfunction when pressed and release immediately and could be used toengage or disengage the cruise control mode when pressed for a longerperiod of time.

A steering sensor 242 senses a turning of the handlebar 244 and sends asignal representative of the orientation of the handlebar to the ECU200. The steering sensor 242 can be in the form of a rheostat ormagnetic switches which are activated when the handlebar 244 is turnedbeyond a certain angle. Although it could be used on other types ofvehicles, the steering sensor 242 would preferably be used in a personalwatercraft, such as personal watercraft 70. Since personal watercraftare steered by redirecting the jet of water created by the jet pump, theamount of steering provided at low engine speeds may be insufficient toaccomplish some tasks. Therefore the steering sensor 242 can be used incontrolling the engine 202 in what is known as an off-throttle steeringoperation mode. In the off-throttle steering operation mode, when theengine speed is below a predetermined engine speed, the ECU 200 causesthe engine speed to be increased upon receiving a signal from thesteering sensor 242 that the handlebar 244 has been turned, as will bedescribed in greater detail below. This will provide additional steeringcapability. U.S. Pat. No. 6,405,669, entitled “Watercraft withSteer-Response Engine Speed Controller”, issued on Jun. 18, 2002, theentirety of which is incorporated herein, describes a system forcontrolling an engine in an off-throttle steering operation mode.

Turning now to FIG. 5, a method of controlling of the ignition system216 and fuel injection systems 218 is illustrated. As would beunderstood by those skilled in the art, actual methods of controllingthese systems are more complex than what is illustrated in FIG. 5. FIG.5 is provided to give a basic understanding of such a method. The firststep 252 of the method consists in sensing the current position of thethrottle valve 212 (TVP_(C)) by using the throttle valve position sensor210. Based on the TVP_(C), the ECU 200 adjusts the ignition at step 254and the injection at step 256. Although shown as occurring in parallel,it should be understood that steps 254 and 256 could occur in series.Step 254 can consist of adjusting the timing of the ignition and/orchanging the number of sparks per ignition event. Step 256 can consistof adjusting the timing of the fuel injection and/or changing thequantity of fuel being injected per ignition event. The ECU 200determines the adjustments for steps 254, 256 by obtaining the ignitionand injection values from engine control maps stored in its memory whichcorrespond to the TVP_(C). Alternatively, the ECU 200 could find thevalues corresponding to a change over time in the TVP_(C) or by applyingan algorithm based on the TVP_(C). Although not illustrated in FIG. 5,it is contemplated that the ECU 200 could use at least one additionalinput obtained from one of the sensors shown in FIG. 4 to perform steps254 and 256, such as the engine speed sensor 238. After completing steps254 and 256, the ECU returns to the start 250 of the method and repeatssteps 252 to 256 again. An increase in the degree of opening of thethrottle valve 212 results in an increase in the speed of the engine202, while a decrease in the degree of opening of the throttle valve 212results in a decrease in the speed of the engine 202.

As will become apparent, some embodiments of the present invention relyon the current speed of the vehicle as obtained by the vehicle speedsensor 208 to control the engine 20. However, under some conditions, thespeed of the vehicle sensed by the vehicle speed sensor 208 can bedifferent from the actual speed of the vehicle. For example, duringoperation, a personal watercraft, such as personal watercraft 70, cansometimes lose contact with the surface of the water in which it isbeing operated due to rough water conditions. If this watercraft isequipped with a vehicle speed sensor 208 in the form of a paddle wheelor pitot tube, as described above, when the paddle wheel is no longer incontact with the water, it will start to spin more slowly which resultsin the vehicle speed sensor 208 reading a speed of the vehicle which ismuch lower than the actual current speed of the vehicle. This wouldresult in the ECU 200 improperly controlling the engine 200 since theECU 200 would attempt to control the engine 202 on a sensed speed whichis different from the actual speed of the vehicle. Similar conditionsmay exist in other vehicles and with different types of vehicle speedsensors 208.

As shown in FIG. 6, the ECU 200 can be programmed to ignore largevariations in the readings for a short period of time by the vehiclespeed sensors 208 that can occur during the operation of the vehicle.After initiating the program (step 260), the first step 262 consists insensing the current speed of the vehicle (V_(C)) by using the vehiclespeed sensor 208. The ECU 200 then stores the value of V_(C) in itsmemory as the value of V₁ at step 264. The current speed of the vehicle(V_(C)) is then sensed once again by using the vehicle speed sensor 208at step 266. At step 268, the ECU 200 then compares the value of V_(C)sensed at step 266 to the value of V₁ (which corresponds to thepreviously sensed value of V_(C)). If the difference between V_(C) andV₁ is less than a predetermined maximum acceptable variation in vehiclespeed (ΔV), the ECU 200 uses the value of V_(C) sensed at step 266 tocontrol the engine 202. The ECU then returns to step 264 where the valueof V_(C) sensed at step 266 is stored as the value of V₁ and the programis repeated. If, at step 268, the difference between V_(C) and V₁ isgreater than or equal to ΔV, which is indicative of an abnormal suddenvariation in the vehicle speed as read by the vehicle speed sensor 208,then the ECU 200 ignores the sudden variation in the vehicle speed. Todo so, a timer is initiated at step 270 (time (t) is equal to zero). TheECU 200 then uses V₁ as the value of V_(C)(step 272) to control of theengine 202 rather than using the value of V_(C) obtained from thevehicle speed sensor 208. The ECU 200 continues to use this value tocontrol the engine 202 until a predetermined amount of time (t₁) haselapsed (step 274). Once the predetermined amount of time has elapsed,the program returns to step 264 and is repeated. ΔV is preferablyselected to be larger than what would be normally possible for thevehicle under normal circumstance. For example, ΔV could be selected tobe greater than the change of vehicle speed that would occur under themaximum possible acceleration of the vehicle. The predetermined amountof time t₁ is preferably selected based on the amount of time for whichit is expected that a false reading should occur. This amount isgenerally determined experimentally. For the watercraft example givenabove, the amount of time would correspond to the amount of time forwhich it is expected that the watercraft will not be in contact with thewater. Should the watercraft not be in contact with the water for longerthan time t₁, the program upon returning to step 268 will go once againthrough steps 270 to 274.

Turning now to FIG. 7, a method, beginning at step 300, of limiting themaximum vehicle speed will be explained. One of the advantages oflimiting the maximum vehicle speed, rather then limiting the maximumengine speed or torque like in the prior art, is that regardless of theload on the vehicle (within the physical limitations of the vehicleobviously), the vehicle will be able to reach its maximum speed. In theprior art systems which limit the maximum engine speed or torque, forthe same maximum engine speed or torque, the speed of the vehicle variesdepending on the load of the vehicle. However, it is contemplated thatthe present method could be used in combination with an engine speed ortorque limiting systems, such that the physical limitations of theengine 202 are not exceeded even though a maximum vehicle speed may nothave been reached yet, thus preventing damage to the engine 202.

The first step 302 of the present method consists in sensing theposition of the throttle operator 206 (throttle operator position (TOP))by using the throttle operator position sensor 204. Based on the TOP,the ECU 200 then determines the corresponding position of the throttlevalve 212 (desired throttle valve position (TVP_(D))) at step 304,either by applying an algorithm, by looking for the corresponding valuein a control map, or both. At step 306, the current position of thethrottle valve 212 (current throttle valve position (TVP_(C))) is sensedby the throttle valve position sensor 210. Step 306 may be omitteddepending on the type of throttle valve actuator 214 being used sincesome throttle valve actuators 214 do not require a throttle valveposition sensor 210, as explained above. Then, at step 308, the ECU 200determines whether the current vehicle speed (V_(C)) is greater than thepredetermined maximum vehicle speed (V_(MAX)). The value of V_(MAX) canbe stored in the ECU 200 by the vehicle manufacturer such that it ispermanently stored in therein, or it can be contained in the key 222 or224 used with the vehicle as explained above, or it could be manuallyinput by a user of the vehicle, or it could also be determined by acondition of the vehicle as described below with respect to FIG. 12. If,at step 308, the current vehicle speed exceeds the predetermined maximumvehicle speed, the ECU 200 sends a signal to the throttle valve actuator214 to decrease degree of opening of the throttle valve 212 (step 310).The ECU 200 then returns to the start 300. If, at step 308, the currentvehicle speed is less than the predetermined maximum vehicle speed,then, at step 312, the ECU 200 verifies if the current throttle valveposition is equal to the desired throttle valve position (as determinedat step 304). If it is, then no action is taken and the ECU 200 returnsto the start 300. If the current throttle valve position is not equal tothe desired throttle valve position, then if the current throttle valveposition is greater than the desired throttle valve position (step 314)the ECU 200 causes the throttle valve actuator 214 to decrease thedegree of opening of the throttle valve 212 (step 316) and then the ECU200 returns to step 308. If at step 314 the current throttle valveposition is not greater than the desired throttle valve position and thecurrent vehicle speed is less than the predetermined maximum vehiclespeed (step 318), the ECU 200 causes the throttle valve actuator 214 toincrease the degree of opening of the throttle valve 212 (step 320) andthen the ECU 200 returns to step 308. If, on the other hand, at step 314the current throttle valve position is not greater than the desiredthrottle valve position and the current vehicle speed is greater thanthe predetermined maximum vehicle speed (step 318), the ECU 200 returnsto the start 300, and once it reaches step 308 it will cause thethrottle valve actuator 214 to decrease degree of opening of thethrottle valve 212 at step 310. Step 318 is present to ensure that thepredetermined maximum speed of the vehicle has not been exceeded sincestep 308 has been executed. The method illustrated in FIG. 7 is suchthat if the current vehicle speed is equal to the predetermined maximumvehicle speed, the degree of opening of the throttle valve 212 is notincreased notwithstanding a fact that the signal representative of thethrottle operator position communicated to the ECU 200 indicates adesire by the driver to increase the speed of the vehicle.

Should the vehicle speed sensor 208 fail during the operation of theengine 202, the ECU 200 stops using an engine control method based onthe vehicle speed, such as the one illustrated in FIG. 7, and defaultsto an engine control method based on the engine speed or engine torque.The failure of the vehicle speed sensor 208 may be due to an electricalproblem, an electronic problem (loss of the GPS signal when a GPS unitis used for example), a mechanical failure of the sensor 208 (a brokenpaddle on a paddle wheel type of sensor for example), or by debris (aclogged pitot tube for example). During the engine control method basedon the engine speed or engine torque, the ECU 200 limits the operationof the engine 202 to one of a default maximum engine speed and a defaultmaximum engine torque, instead of a maximum vehicle speed as in FIG. 7.The default maximum engine speed or the default maximum engine torque ispreferably selected such that when the engine 202 operates at thedefault maximum engine speed or the default maximum engine torque, thevehicle speed is less than the predetermined maximum vehicle speed ofthe method of FIG. 7.

FIG. 8 illustrates a method, starting at step 330, of controlling theengine 202 which limits the operation of the engine 202 to a defaultmaximum engine speed in case of a vehicle speed sensor 208 failure. Itis contemplated that the same method could be applied by using a defaultmaximum engine torque. At step 332, the ECU 200 verifies if there is afailure of the vehicle speed sensor 208. The ECU 200 determines thatthere is a failure of the vehicle speed sensor 208 when it no longerreceives a signal from the vehicle speed sensor 208 or the signal isinconsistent. If the vehicle speed sensor 208 operates normally, thenthe ECU 200 continues to operate the engine 202 of the vehicle normally(normal operation 333). Normal operation 333 of the engine 202 includes,but is not limited to, the control method illustrated in FIG. 7. Ifthere is a failure of the vehicle speed sensor 208, the ECU 200 thenverifies if the engine 202 is stopped at step 334, by removal of thekey, pressing of the stop button, or otherwise. Stopping the engine 202reinitiates the control method (step 330). Once the ECU 200 returns tostep 332, and if the problem that caused the failure of the vehiclespeed sensor 208 has been corrected, the ECU 200 returns to the normaloperation 333 of the engine 202. Although not illustrated, it iscontemplated that if a failure of the vehicle speed sensor 208 isdetected at step 332, the ECU 200 will cause a signal, either audible orvisual, to be emitted or cause a maintenance code to be displayed suchthat the driver of the vehicle is made aware of the failure.

If there is a failure of the vehicle speed sensor 208 and the engine hasnot been stopped, then the ECU 200 uses a control method having stepssimilar to those used in the method illustrated in FIG. 7, but usingengine speed instead of vehicle speed. The position of the throttleoperator 206 is sensed (step 336) (throttle operator position (TOP)) byusing the throttle operator position sensor 204. Based on the TOP, theECU 200 then determines the corresponding position of the throttle valve212 (desired throttle valve position (TVP_(D))) at step 338, either byapplying an algorithm, by looking for the corresponding value in acontrol map, or both. At step 340, the current position of the throttlevalve 212 (current throttle valve position (TVP_(C))) is sensed by thethrottle valve position sensor 210. Then, at step 342, the ECU 200determines whether the current engine speed (RPM_(C)) is greater thanthe default maximum engine speed (RPM_(MAX)). The value of RPM_(MAX) canbe stored in the ECU 200 by the vehicle manufacturer, or it can becontained in the key 222 or 224 used with the vehicle as explainedabove, or it could be manually input by a user of the vehicle, or itcould also be determined by a condition of the vehicle as describedbelow with respect to FIG. 11. If, at step 342, the current engine speedexceeds the default maximum engine speed, the ECU 200 sends a signal tothe throttle valve actuator 214 to decrease degree of opening of thethrottle valve 212 (step 344). The ECU 200 then returns to step 334. If,at step 342, the current engine speed is less than the default maximumengine speed, then, at step 346, the ECU 200 verifies if the currentthrottle valve position is equal to the desired throttle valve position(as determined at step 338). If it is, then no action is taken and theECU 200 returns to the step 334. If the current throttle valve positionis not equal to the desired throttle valve position, then if the currentthrottle valve position is greater than the desired throttle valveposition (step 348) the ECU 200 causes the throttle valve actuator 214to decrease the degree of opening of the throttle valve 212 (step 350)and then the ECU 200 returns to step 334. If at step 348 the currentthrottle valve position is not greater than the desired throttle valveposition and the current engine speed is less than the default maximumengine speed (step 352), the ECU 200 causes the throttle valve actuator214 to increase the degree of opening of the throttle valve 212 (step354) and then the ECU 200 returns to step 334. If, on the other hand, atstep 348 the current throttle valve position is not greater than thedesired throttle valve position and the current engine speed is greaterthan the default maximum engine speed (step 352), the ECU 200 returns tothe step 334, and once it reaches step 342 it will cause the throttlevalve actuator 214 to decrease degree of opening of the throttle valve212 at step 344. Step 352 is present to ensure that the default maximumengine speed has not been exceeded since step 342 has been executed. Themethod illustrated in FIG. 8 is such that if the current engine speed isequal to the default maximum engine speed, the degree of opening of thethrottle valve 212 is not increased notwithstanding a fact that thesignal representative of the throttle operator position communicated tothe ECU 200 indicates a desire by the driver to increase the speed ofthe vehicle. The ECU 200 will continue to control the engine 202 byapplying steps 336 to 354 (as required) until the engine has beenstopped (step 334) (and then restarted) and the problem that caused thefailure of the vehicle speed sensor 208 has been corrected. Only thenwill normal operation 333 of the engine 202 resume.

Turning now to FIG. 9A, a method, beginning at step 360, of controllingan engine 202 in a cruise control mode will be explained. Although themethod illustrated in FIG. 9A is particularly well suited for a personalwatercraft, such as personal watercraft 70, as they do not typicallyhave a brake lever that could be used to disengage the cruise controlmode as in other vehicles, it is contemplated that this method couldalso be used in other types of vehicles. At step 362, the ECU 200determines if the cruise control operation mode has been engaged. Thecruise control operation mode would typically be engaged by using thecruise control switch 240 described above. If the cruise control modehas not been engaged, in the case of a personal watercraft, the ECU 200then determines if the current engine speed (RPM_(C)) is less than orequal to an engine speed where an off-throttle steering operation modeshould be engaged (RPM_(OTS)) (step 364). If it is not, the normaloperation 366 of the engine 202 is applied by the ECU 200. Normaloperation 366 of the engine 202 includes, but is not limited to, thecontrol method illustrated in FIG. 7. If, on the other hand, RPM_(C) isless than or equal to RPM_(OTS), than the off-throttle steering (OTS)operation mode (step 368) is applied by the ECU 200. The OTS operationmode 368 will be described in greater detail below with respect to FIG.10. In the case of land vehicles, steps 364 and 368 are omitted, and ifthe cruise control operation mode has not been engaged (step 362) thenthe ECU 200 continues to operate the engine 202 in the normal operationmode 366. If at step 362, the ECU 200 determines that the cruise controloperation mode has been engaged, then the cruising speed (V_(CRUISE)) ofthe vehicle is set at step 370. The cruising speed can be stored in theECU 200 by the vehicle manufacturer, or it can be contained in the key222 or 224 used with the vehicle as explained above, or it could bemanually input by a user of the vehicle, or, in a preferred embodiment,the cruising speed is set to be equal to the speed of the vehicle at theinstant when the cruise control operation mode is engaged. Then at step372, the ECU 200 determines if the current throttle operator position(TOP_(C)) is less than or equal to a reference throttle operatorposition (TOP_(R)). The reference throttle operator position can bestored in the ECU 200 by the vehicle manufacturer, or it can becontained in the key 222 or 224 used with the vehicle as explainedabove, or it can be set to be equal to the throttle operator position atthe instant when the cruise control operation mode is engaged, in whichcase the ECU 200 would determine if the current throttle operatorposition is less than the reference throttle operator position. Thecurrent throttle operator position is considered to be less than thereference throttle operator position when the throttle operator islocated between the reference throttle operator position and the fullyreleased position of the throttle operator or at the fully releasedposition of the throttle operator. Alternatively, the reference throttleoperator position can be a fully released position of the throttleoperator in which case the ECU 200 would determine if the currentthrottle operator position is equal to the reference throttle operatorposition. The ECU 200 then determines at step 376 if the driver of thevehicle has actively disengaged the cruise control operation mode,either by pressing the cruise control switch 240, or stopping the engineby pressing the engine stop switch or removing the key 222 or 224. Ifthe cruise control operation mode has been disengaged by the user, thenthe ECU 200 returns to step 360. If the cruise control operation modehas not been disengaged by the user, then the ECU 200 causes thethrottle valve actuator 214 to decrease the degree of opening of thethrottle valve 212 (step 380) if the current vehicle speed is greaterthan the cruising speed (step 378), and to increase the degree ofopening of the throttle valve 212 (step 384) if the current vehiclespeed is less than the cruising speed (step 378). Once either of steps380 or 384 has been completed or if the current vehicle speed is equalto the cruising speed, the ECU 200 returns to step 372. This isparticularly advantageous as it allows the vehicle to maintain aconstant cruising speed even though the load on the vehicle varies, duefor example to changes in the terrain for land vehicles, or the movementof a water skier being towed by the vehicle in the case of a personalwatercraft. If at step 372 the current throttle operator position isless than or equal to the reference throttle operator position, which isindicative of the driver's desire to reduce the speed of the vehicle,then the cruise control operation mode is disengaged (step 374) and thevehicle cruising speed is no longer maintained even though the driver ofthe vehicle has not actively disengaged the cruise control operationmode. The inclusion of step 372 allows the driver of the vehicle to movethe throttle operator 206 to a more comfortable position, such as themaximum throttle operator position for thumb or finger-actuated throttlelevers, while continuing to operate the vehicle at the vehicle cruisingspeed. For example, when the driver of a personal watercraft reaches thecruising speed he desires, he presses the cruise control switch 240. Thedriver can then move the throttle operator to an increased throttleoperator position, the maximum position for example, which is morecomfortable and easier to maintain. As long as the driver does not pressthe cruise control switch 240, or stop the engine, or release thethrottle operator such that it moves to a position which is less thanthe position of the throttle operator when the cruise control switch 240was first pressed, the cruising speed will be maintained. Should thedriver press the cruise control switch 240 again, or stop the engine, orrelease the throttle operator such that it moves to a position which isless than the position of the throttle operator when the cruise controlswitch 240 was first pressed, then the cruise control mode will bedisengaged and the speed of the vehicle will once again be controlledbase on the throttle operator position.

Turning now to FIG. 9B, an alternative method, beginning at step 360, ofcontrolling an engine 202 in a cruise control mode will be explained.The method of FIG. 9B is similar to the method illustrated in FIG. 9Awith the exception of steps 372 and 374 which have been eliminated. Forsimplicity, similar steps have been labeled with the same referencenumerals as FIG. 9A and only those which are different will be describedbelow. In the method of FIG. 9B, once the cruising speed is set at step370, the ECU 200 then determines at step 376 if the driver of thevehicle has actively disengaged the cruise control operation mode,either by pressing the cruise control switch 240, or stopping the engineby pressing the engine stop switch or removing the key 222 or 224 asdescribed above. However, in this embodiment, the cruise controloperation mode can be actively disengaged by the driver by actuating alever from a rest position. If at step 376 the ECU determines that thedriver has actuated the lever, the cruise control operation mode isdisengaged. In a preferred embodiment of the method illustrated in FIG.9B, the lever is the throttle operator 206, in the form of a thumb orfinger actuated lever. Once the driver of the vehicle has engage thecruise control operation mode, the driver can let go of the throttleoperator 206 and the vehicle will operate in the cruise controloperation mode until the driver actuates the throttle operator 206again. It is contemplated that the lever could be a separate leverdisposed on a side of the handlebar 244 of the vehicle opposite the sideon which the throttle operator 206, for example a brake lever. If thecruise control operation mode has been disengaged by the user, then theECU 200 returns to step 360 as described above with respect to FIG. 9A.If the cruise control operation mode has not been disengaged by the userat step 376, then the method proceeds as described above with respect toFIG. 9A, with the exception that steps 380, 384, and a negativedetermination at step 382 return to step 376.

Turning now to FIG. 10, a method, starting at step 400, of controllingan engine 202 in an off-throttle steering (OTS) operation mode will bedescribed. The method illustrated in FIG. 10 is particularly well suitedfor personal watercraft and other jet propelled marine vehicles as theyrequire a certain amount of thrust in order to be steered. As mentionedwith respect to the method illustrated in FIG. 9A, the ECU 200 operatesthe engine in the OTS operation mode when the current engine speed(RPM_(C)) is less than or equal to a predetermined engine speed(RPM_(OTS)). In the OTS operation mode, the ECU 200 first determines ifthe handlebar 244 has been turned at step 402 based on a signal receivedfrom the steering sensor 242. It is contemplated that step 402 couldinstead determine if the handlebar 244 has been turned by more than apredetermined angle. If the handlebar 244 has been turned, then the ECU200 determines if the current engine speed (RPM_(C)) is less than apredetermined engine speed (RPM_(STEER)) which provides sufficientthrust to steer the vehicle (step 404). If it is not, then the ECU 200returns to step 400. If the current vehicle speed is less than thepredetermined engine speed (RPM_(STEER)), the ECU 200 causes thethrottle valve actuator 214 to increase the degree of opening of thethrottle valve 212 thereby increasing the speed of the engine in orderto provide sufficient thrust to steer the vehicle and then returns tostep 400. If at step 402, it is determined that the handlebar 244 is notturned, then the throttle operator position is sensed (step 408), thedesired throttle valve position is determined by the ECU 200 (step 410),and the current throttle valve position is sensed (step 412) in the samemanner as described above with respect to the methods illustrated inFIGS. 7 and 8. The ECU 200 then determines if the current throttle valveposition is equal to the desired throttle valve position (step 414). Ifit is not, then the ECU 200 causes the throttle valve actuator 214 todecrease the degree of opening of the throttle valve 212 (step 418) ifthe current throttle valve position is greater than the desired throttlevalve position (step 416), and to increase the degree of opening of thethrottle valve 212 (step 422) if the current throttle valve position isless than the desired throttle valve position (step 420). Once either ofsteps 418 or 422 has been completed or if the current throttle valveposition is equal to the desired throttle valve position, the ECU 200goes to step 424. At step 424, the ECU 200 determines if the currentengine speed is still less than or equal the predetermined engine speedRPM_(OTS). If it is, the ECU 200 returns to step 400 and continues tocontrol the engine 202 in the OTS operation mode. If it is not, the ECU200 goes to step 426, ceases to control the engine 202 in the OTSoperation mode, and returns to the previous operation mode such as theones illustrated in FIGS. 9A and 9B. As previously mentioned, U.S. Pat.No. 6,405,669, entitled “Watercraft with Steer-Response Engine SpeedController”, issued on Jun. 18, 2002, the entirety of which isincorporated herein, also describes a system for controlling an enginein an OTS operation mode.

Steps 310, 316, 320, 344, 350, 354, 380, 384, 406, 418, and 422described above can be achieved by causing the throttle valve actuator214 to decrease or increase, as the case may be, the degree of openingof the throttle valve 212 in a single step that would bring the currentvehicle speed (for steps 310, 380, and 384), the current engine speed(for steps 344 and 406), or the current position of the throttle valve212 (for steps 316, 320, 350, 354, 380, 384, 418, and 422) to thedesired value. However, in a preferred embodiment, these steps onlydecrease or increase, as the case may be, the degree of opening of thethrottle valve 212 in multiple stages and the ECU 200 runs through thecorresponding method between each stage to determine whether to applythe same step again or if a change has occurred which requires adifferent step to be applied. For example, in view of the methodillustrated in FIG. 7, a land vehicle which starts to go downhill mayrequire step 310 to be applied even though step 320 was being appliedpreviously. This provides for a smoother operation of the engine 202 andfor a quicker response to changes in the operation of the vehicle.

As previously mentioned with respect to some of the previously describedcontrol methods, a condition of the vehicle can also be used todetermine the operational limit of the vehicle or engine 202. One suchcondition is the vehicle operation direction (forward or reverse). It isdesirable that the performance of the vehicle or engine 202 be morelimited when the vehicle is operated in the reverse direction than whenit is operated in the forward direction.

FIG. 11 illustrates a method, starting at step 430, of establishing thespeed limit of the engine 202 by limiting the degree of opening of thethrottle valve 212 based on the direction of operation of the vehicle.During operation of the vehicle, the ECU 200 will not cause the throttlevalve actuator 214 to move the throttle valve 212 beyond the maximumdegree of opening of the throttle valve 212 (TVP_(MAX)) as determined bythe method, notwithstanding a fact that the signal representative of thethrottle operator position communicated to the ECU 200 indicates adesire by the driver to increase the degree of opening of the throttlevalve 212. When the degree of opening of the throttle valve 212 is lessthan the maximum degree of opening of the throttle valve 212, the ECU200 controls the opening of the throttle valve 212 based on the signalreceived from the throttle operator position sensor 204. The vehicleoperation direction sensor, described above, sends a signal indicativeof the vehicle operation direction to the ECU 200 at step 432. If thevehicle is operated in the forward direction (step 434), then themaximum degree of opening of the throttle valve is limited to a firstmaximum degree of opening of the throttle valve (TVP₁) (step 436). Ifthe vehicle is operated in the reverse direction (step 438), then themaximum degree of opening of the throttle valve is limited to a secondmaximum degree of opening of the throttle valve (TVP₂) (step 440) whichis less than the first maximum degree of opening of the throttle valve.Therefore, the engine 202 can reach a higher speed when the vehicle isoperated in the forward direction than in the reverse direction.

FIG. 12 illustrates a method, starting at step 450, of establishing thespeed limit of the vehicle based on the direction of operation of thevehicle. During operation of the vehicle, the ECU 200 will control theengine 202 such that the vehicle does not exceed the maximum vehiclespeed (V_(MAX)) as determined by the method, notwithstanding a fact thatthe signal representative of the throttle operator position communicatedto the ECU 200 indicates a desire by the driver to increase the vehiclespeed. When the vehicle speed is less than the maximum vehicle speed,the ECU 200 controls the opening of the throttle valve 212 based on thesignal received from the throttle operator position sensor 204. Thevehicle operation direction sensor, described above, sends a signalindicative of the vehicle operation direction to the ECU 200 at step452. If the vehicle is operated in the forward direction (step 454),then the maximum vehicle speed is limited to a maximum forward vehiclespeed (V₁) (step 456). If the vehicle is operated in the reversedirection (step 458), then the maximum vehicle speed is limited to amaximum reverse vehicle speed (V₂) (step 460) which is less than themaximum forward vehicle speed. Therefore, the vehicle can reach a higherspeed when the vehicle is operated in the forward direction than in thereverse direction.

FIG. 13 illustrates a method, starting at step 470, of establishing theoperational limit of the vehicle by limiting the operational limit ofthe vehicle based on the direction of operation of the vehicle. When thevehicle operates in a forward direction, the ECU 200 limits the maximumspeed of the vehicle, and when the vehicle operates in a reversedirection, the ECU 200 limits the maximum degree of opening of thethrottle valve, as described in detail below. It is also contemplatedthat the ECU 200 could limit the maximum degree of opening of thethrottle valve when the vehicle operates in a forward direction andlimit the maximum speed of the vehicle when the vehicle operates in areverse direction.

The vehicle operation direction sensor, described above, sends a signalindicative of the vehicle operation direction to the ECU 200 at step472. If the vehicle is operated in the forward direction (step 474),then the maximum vehicle speed (V_(MAX)) is limited to a maximum forwardvehicle speed (V₁) (step 476). During forward operation of the vehicle,the ECU 200 will control the engine 202 such that the vehicle does notexceed the maximum vehicle speed (V_(MAX)) as determined by the method,notwithstanding a fact that the signal representative of the throttleoperator position communicated to the ECU 200 indicates a desire by thedriver to increase the vehicle speed. When the vehicle speed is lessthan the maximum vehicle speed, the ECU 200 controls the opening of thethrottle valve 212 based on the signal received from the throttleoperator position sensor 204. If the vehicle is operated in the reversedirection (step 478), then the maximum degree of opening of the throttlevalve (TVP_(MAX)) is limited to a maximum degree of opening of thethrottle valve (TVP₂) (step 480). TVP₂ is selected such that when theengine operates at that degree of opening of the throttle valve 212, thespeed of the vehicle is less than the maximum forward vehicle speed.During reverse operation of the vehicle, the ECU 200 will not cause thethrottle valve actuator 214 to move the throttle valve 212 beyond themaximum degree of opening of the throttle valve 212 (TVP_(MAX)) asdetermined by the method, notwithstanding a fact that the signalrepresentative of the throttle operator position communicated to the ECU200 indicates a desire by the driver to increase the degree of openingof the throttle valve 212. When the degree of opening of the throttlevalve 212 is less than the maximum degree of opening of the throttlevalve 212, the ECU 200 controls the opening of the throttle valve 212based on the signal received from the throttle operator position sensor204. Therefore, the engine 202 can reach a higher speed when the vehicleis operated in the forward direction than in the reverse direction.

For the methods illustrated in FIGS. 11 to 13, it is contemplated thatthe ECU 200 would control the engine 202 such that the rate of change inengine speed and/or engine torque and/or throttle valve position isdifferent depending on the direction of operation of the vehicle. It isalso contemplated that an override switch could be added to the vehiclewhich, when pressed, would make the ECU 200 control the engine 202 suchthat the throttle valve position can exceed the maximum degree ofopening of the throttle valve (step 440 in FIG. 11, step 480 in FIG. 13)or such that the speed of the vehicle can exceed the maximum reversevehicle speed (step 460 in FIG. 12), as the case may be, when thevehicle is operated in the reverse direction.

Turning now to FIG. 14 a method of controlling the engine 202 of avehicle when a sudden acceleration occurs will be described. Forsimplicity, the method will be described with respect to the ATV 150,but it should be understood that it could apply to any land vehicle,such as snowmobile 10. During operation, the powered wheels 158 of theATV 150 can sometimes lose contact with the surface on which the ATV 150is operated due to bumps. When this occurs, the rotation of the wheels158 is no longer restrained since they are in the air and this willcause them to start to accelerate suddenly if the throttle operator 206is not released by the driver of the ATV 150. When the wheels 158 makecontact with the ground once again, the wheels 158 are suddenlydecelerated which may result in components of the ATV 150 being damaged.If the ATV is equipped with a vehicle speed sensor 208 which senses thespeed of rotation of a wheel 158 or of one of the shafts transmittingpower to the wheel 158, as described above, then it is possible todetermine that such a condition has occurred, and it is possible to takeappropriate actions as described below.

As shown in FIG. 14, the ECU 200 can be programmed to reduce the speedof rotation of the engine 202 when large increases the readings taken bythe vehicle speed sensor 208. After initiating the program (step 500),the first step 502 consists in sensing the current speed of the vehicle(V_(C)) by using the vehicle speed sensor 208. The ECU 200 then storesthe value of V_(C) in its memory as the value of V₁ at step 504. Thecurrent speed of the vehicle (V_(C)) is then sensed once again by usingthe vehicle speed sensor 208 at step 506. At step 508, the ECU 200 thencompares the value of V_(C) sensed at step 506 to the value of V₁ (whichcorresponds to the previously sensed value of V_(C)). If the differencebetween V_(C) and V₁ is less than a predetermined maximum acceptablevariation in vehicle speed (ΔV), the ECU 200 returns to step 504 wherethe value of V_(C) sensed at step 506 is stored as the value of V₁ andthe program is repeated. If, at step 508, the difference between V_(C)and V₁ is greater than or equal to ΔV, which is indicative of a suddenincrease in the speed of rotation of the wheels 158 of the ATV 150 mostlikely caused by the wheels 158 no longer being in contact with theground, then the ECU 200 moves to step 510. At step 510 the ECU 200 willreduce the speed of rotation of the engine 202 in order to reduce tospeed of rotation of the wheel 158 such that the degree of decelerationof the wheels 158 when they make contact once again with the ground isminimized. In order to reduce the speed of rotation of the engine 202,the ECU 200 sends a signal to the throttle valve actuator 214 to reducethe degree of opening of the throttle valve 212. It is contemplated thatthe speed of rotation of the engine 202 could also be reduced byadjusting the ignition and injection timing and the amount of fuel beinginjected. The program then returns to step 504 and is repeated. ΔV ispreferably selected to be larger than what would be normally possiblefor the ATV 150 under normal circumstance (i.e. with the wheels 158 incontact with the ground). For example, ΔV could be selected to begreater than the change of vehicle speed that would occur under themaximum possible acceleration of the ATV 150.

Modifications and improvements to the above-described embodiments of thepresent invention may become apparent to those skilled in the art. Theforegoing description is intended to be exemplary rather than limiting.The scope of the present invention is therefore intended to be limitedsolely by the scope of the appended claims.

1. A vehicle comprising: a vehicle body; a straddle seat for a driver,the seat being associated with the vehicle body; a handlebar forsteering the vehicle disposed forwardly of the straddle seat; an engineassociated with the vehicle body for powering the vehicle, the enginehaving at least one combustion chamber; an electronic control unit (ECU)on the vehicle for controlling an operation of the engine; a throttlebody in fluid communication with the at least one combustion chamber; athrottle valve disposed in the throttle body for controlling an amountof air supplied to the at least one combustion chamber; a throttle valveactuator operatively connected to the throttle valve and in electroniccommunication with the ECU; a throttle operator mounted on thehandlebar; a throttle operator position sensor for sensing a throttleoperator position and in electronic communication with the ECU forsending a signal representative of a throttle operator position to theECU; and a vehicle speed sensor for sensing a vehicle speed and inelectronic communication with the ECU for sending a signalrepresentative of a vehicle speed to the ECU, the ECU sending a controlsignal to the throttle valve actuator based on the throttle operatorposition signal and the vehicle speed signal, the throttle valveactuator adjusting a degree of opening of the throttle valve in responseto the control signal, if the vehicle speed is lower than apredetermined maximum vehicle speed, the control signal causing thethrottle valve actuator to adjust the degree of opening of the throttlevalve based on the throttle operator position signal, and if the vehiclespeed is higher than the predetermined maximum vehicle speed, thecontrol signal causing the throttle valve actuator to reduce the degreeof opening of the throttle valve.
 2. The vehicle of claim 1, wherein ifthe vehicle speed is higher than the predetermined maximum vehiclespeed, the control signal causes the throttle valve actuator to reducethe degree of opening of the throttle valve notwithstanding a fact thatthe signal representative of the throttle operator position communicatedto the ECU indicates a desire by the driver to increase the speed of thevehicle.
 3. The vehicle of claim 1, wherein, if the vehicle speed isequal to the predetermined maximum vehicle speed, the degree of openingof the throttle valve is not increased notwithstanding a fact that thesignal representative of the throttle operator position communicated tothe ECU indicates a desire by the driver to increase the speed of thevehicle.
 4. The vehicle of claim 3, wherein the throttle operator isselected from a group consisting of a thumb-actuated throttle lever, afinger-actuated throttle lever, and a twist grip.
 5. The vehicle ofclaim 4, further comprising a jet propulsion unit operatively connectedto the engine; wherein the vehicle body has a hull and a deck disposedon the hull; and wherein the engine is disposed between the hull and thedeck.
 6. The vehicle of claim 5, wherein the vehicle speed sensor isselected from a group consisting of a paddle wheel, a GPS unit, and apitot tube.
 7. The vehicle of claim 4, further comprising only threewheels associated with the vehicle body.
 8. The vehicle of claim 4,further comprising at least one of at least four wheels associated withthe vehicle body and an endless track associated with the vehicle body.9. The vehicle of claim 1, wherein the vehicle speed sensor includes aGPS unit.
 10. The vehicle of claim 1, wherein the vehicle speed sensorsenses a rotational speed of a shaft of the vehicle.
 11. The vehicle ofclaim 1, further comprising: a fuel injection system for injecting fluidin the at least one combustion chamber; an ignition system for ignitinga mixture of fuel and air in the at least one combustion chamber; and athrottle valve position sensor for sensing the degree of opening of thethrottle valve and in electronic communication with the ECU for sendinga signal representative of a throttle valve position to the ECU, the ECUcontrolling at least one of the fuel injection system and the ignitionsystem based on the throttle valve position signal.
 12. The vehicle ofclaim 1, further comprising a throttle valve position sensor for sensingthe degree of opening of the throttle valve and in electroniccommunication with the ECU for sending a signal representative of athrottle valve position to the ECU; wherein the ECU establishes adesired degree of opening of the throttle valve based on the throttleoperator position signal; and wherein the ECU generates the controlsignal both by: (a) comparing the desired degree of opening of thethrottle valve to the degree of opening of the throttle valve, and (b)comparing the vehicle speed to the predetermined maximum vehicle speed.13. The vehicle of claim 1, wherein, when a variation in the vehiclespeed signal occurs which is greater than a predetermined maximumacceptable variation, the ECU ignores the variation in the vehicle speedsignal for a predetermined time delay.
 14. The vehicle of claim 1,wherein, when a failure of the vehicle speed sensor is detected, the ECUlimits the operation of the engine to one of a default maximum enginespeed and a default maximum engine torque; and wherein the one of thedefault maximum engine speed and the default maximum engine torque isselected such that when the engine operates at the one of the defaultmaximum engine speed and the default maximum engine torque, the vehiclespeed is less than the predetermined maximum vehicle speed.
 15. Thevehicle of claim 1, further comprising a key receiver disposed on thevehicle body for receiving one of at least two keys that can be used topermit operation of the vehicle, the key receiver being in electroniccommunication with the ECU; wherein the predetermined maximum vehiclespeed is determined from information contained on the one of the atleast two keys which is received in the key receiver; and wherein thepredetermined maximum vehicle speed is different for each of the atleast two keys.
 16. The vehicle of claim 1, wherein the predeterminedmaximum vehicle speed is permanently stored in the ECU.
 17. The vehicleof claim 1, wherein, when a variation in the vehicle speed signal occurswhich is greater than a predetermined maximum acceptable variation, theECU controls the engine such that a speed of rotation of the engine isreduced.
 18. A method of controlling an engine of a vehicle, the enginehaving at least one combustion chamber, the vehicle having a throttleoperator, a throttle body in fluid communication with the at least onecombustion chamber, a throttle valve disposed in the throttle body forcontrolling an amount of air supplied to the at least one combustionchamber, and a throttle valve actuator operatively connected to thethrottle valve for adjusting a degree of opening of the throttle valve,the method comprising: sensing a throttle operator position; sensing avehicle speed; comparing the vehicle speed to a predetermined maximumvehicle speed; if the vehicle speed is lower than the predeterminedmaximum vehicle speed, adjusting the degree of opening of the throttlevalve based on the throttle operator position; and if the vehicle speedis higher than the predetermined maximum vehicle speed, reducing thedegree of opening of the throttle valve until the vehicle speed is atthe predetermined maximum speed.
 19. The method of claim 18, furthercomprising: if vehicle speed is greater than the predetermined maximumvehicle speed, not implementing a driver instruction to increase thedegree of opening of the throttle valve.
 20. The method of claim 18,further comprising: if vehicle speed is equal to the predeterminedmaximum vehicle speed, not implementing a driver instruction to increasethe degree of opening of the throttle valve.
 21. The method of claim 18,wherein the step of sensing the vehicle speed includes sensing one of arotational speed of a paddle wheel mounted to the vehicle, a rotationalspeed of a shaft of the vehicle, and a pressure of a fluid in which thevehicle is used.
 22. The method of claim 18, wherein the step of sensingthe vehicle speed includes determining a change in position of thevehicle over a period of time based on information obtained from a GPSunit.
 23. The method of claim 18, further comprising: sensing the degreeof opening of the throttle valve; and controlling at least one of a fuelinjection system and an ignition system based on the degree of openingof the throttle valve.
 24. The method of claim 18, further comprisingsensing the degree of opening of the throttle valve; and wherein thestep of adjusting the degree of opening of the throttle valve includes:establishing a desired degree of opening of the throttle valve based onthe throttle operator position; if the desired degree of opening of thethrottle valve is less than the degree of opening of the throttle valve,decreasing the degree of opening of the throttle valve until the degreeof opening of the throttle valve is equal to the desired degree ofopening of the throttle valve; and if the desired degree of opening ofthe throttle valve is greater than the degree of opening of the throttlevalve, increasing the degree opening of the throttle valve until one ofa first condition and a second condition is met, the first conditionbeing that the degree of opening of the throttle valve is equal to thedesired degree of opening of the throttle valve, and the secondcondition being that the vehicle speed is equal to the predeterminedmaximum vehicle speed.
 25. The method of claim 18, further comprising:ignoring a variation in the vehicle speed which is greater than apredetermined maximum acceptable variation for a predetermined timedelay when sensing the vehicle speed; and using the vehicle speed priorto the variation in the vehicle speed when comparing the vehicle speedto the predetermined maximum vehicle speed during the predetermined timedelay.
 26. The method of claim 18, further comprising: sensing forfailure of a vehicle speed sensor; and limiting the engine to one of adefault maximum engine speed and a default maximum engine torque whenfailure of the vehicle speed sensor is sensed, wherein the one of thedefault maximum engine speed and the default maximum engine torque isselected such that when the engine is at the one of the default maximumengine speed and the default maximum engine torque, the vehicle speed islower than the predetermined maximum vehicle speed.
 27. The method ofclaim 18, further comprising: obtaining information contained on a keyinserted in a key receiver of the vehicle; and using the informationcontained on the key to determine the predetermined maximum vehiclespeed.
 28. The method of claim 18, further comprising: reducing a speedof rotation of the engine when a variation in the vehicle speed isgreater than a predetermined maximum acceptable variation.